Hancock's legislation would require approval by voters if it passes the Legislature.

Taxpayers have paid $4 billion for the 13 executions performed since 1978, according to the report, putting the cost of each execution at $308 million.

Despite the cost, victims' advocate Marc Klaas said he disagrees with Hancock's plan.

Klaas' daughter Polly was kidnapped from her bedroom during a slumber party in 1993. Her case became a lightening rod for stricter sentencing, which led to California's Three Strikes law.

The case did not impact the state's death penalty laws. Richard Allen Davis was found guilty of murdering Klaas and was sentenced to death in 1996. He remains on death row.

"There's a guy who kidnapped raped and murdered my 12-year-old daughter who was sentenced to death per the laws of California and now there are people who are working to make laws to spare his life," Klaas said. "It's just absolutely unbelievable."